Chemical spray chambers such as etching chambers often include a window for viewing the spraying activities from the outside of the chamber without the danger of exposure to hazardous chemicals. The windows also allow for access to the mechanical equipment and product inside the chambers for repair or inspection. FIG. 1 shows the existing window for a typical etching spray chamber 106. The windows employ thick glass 101, surrounded by a metal frame 102 of about 20 inches by thirty inches. The frame 102 window 101 assembly is attached to the chamber 106 via ten threaded fasteners 104. Handles are incorporated into the metal frame 105 for handling of the assembly during removal from and attachment to the chamber.
Several problems exist with this design. The first is leaking of the hazardous chemicals from the chamber. Since the frame 102 window 101 assembly is attached by only ten points, the forced chemical spray originating inside the chamber easily leaks past the seal of the window between the fastening points. The acid then dissolves the metal frame 102, fasteners 104 and the acid drips on other equipment in the area resulting in frequent equipment failure. Secondary problems arise from use of the window. The thick glass 101 and metal frame 102 assembly is heavy. In addition the fasteners require twelve minutes to remove and re-install. A total of eighty eight windows are installed on some existing equipment. Simple removal and installation of all of the windows is thus a significant job.
It is therefore an object of the present invention to provide a chemical spray chamber window apparatus that makes it as difficult as possible for pressurized spray to break through the window seal, thus limiting potential leaks of harmful chemicals from the chamber. Assuming that some of the chemicals may leak at some point, it is a further object of the present invention to provide an apparatus that mitigates these potential leaks.
It is another object of the present invention to provide a chemical spray chamber window apparatus that is easily accessible. Elimination of threaded fasteners for access to the window in less than 15 seconds is part of this objective.
It is another object of the present invention to provide a chemical spray chamber window apparatus made of economical materials that will not be effected by acids and other dangerous materials sprayed in the chemical chamber. The design of the apparatus should be such that it is adaptable for existing spray chambers, and is reproducible by automated machining.